Abstract [en]

The social aspect of sustainable and ‘clean’ production/manufacturing technologies is researched and understood by means of Social Life Cycle Assessment (SLCA), a Life Cycle Sustainability Assessment (LCSA) tool, which is still in its infancy. In this paper, a search for all peer-reviewed publications on applied Social LCA, which have appeared in scientific journals, between O’Brien et al (1996) and the latest one at the time of writing (April 2018), was carried out, using Scopus as the repository and using “S-LCA” OR “SLCA” OR “Social LCA” OR “Social Life Cycle Assessment” as search-phrases in title, abstract and keywords of publications, separately. Overall, 213 publications were unearthed, and the trend shows that there has been a near-exponential increase over time. A little over 55% of these publications – 121 to be precise - were applications of S-LCA – often in combination with environmental-LCA and life cycle costing analysis, in an LCSA. This paper discusses the contributions of a selected subset of these 121 publications to the body of S-LCA knowledge, with the focus being restricted to applications in developing and transition economies of the world, on the premise that there is a more urgent need to understand social aspects of production and manufacturing in these parts of the world. A SWOT analysis of S-LCA has been carried out towards the end. There is a consensus among many researchers that while LCC and E-LCA have matured a lot over time, S-LCA, the newest of the trio, is evolving slowly to become a harmonised tool which can serve as an effective complement to the aforesaid two, in life cycle sustainability assessments of products and processes in industry.

Place, publisher, year, edition, pages

Springer Berlin/Heidelberg, 2019

Keywords

Life cycle sustainability assessment, Social life cycle assessment, S-LCA, S-LCA, Social LCA

Abstract [en]

Sweden is one of the largest exporters of pulp and paper products in the world. It follows that huge quantities of sludge rich in carbonaceous organic material and containing heavy metals are generated. This paper carried out a comparative environmental analysis of three different technologies, which can be adopted to produce biochar and recover energy from the biosludge, using landfilling as the reference case. These three thermochemical biosludge management systems—using incineration, pyrolysis, and hydrothermal carbonization (HTC)—were modeled using life cycle assessment (LCA). Heat generated in the incineration process (System A) was considered to be for captive consumption within the kraft pulp mills. It was assumed that the biochars—pyrochar and hydrochar—produced from pyrolysis (System B) and HTC (System C), respectively, were added to the forest soils. The LCA results show that all the alternative systems considerably improve the environmental performance of biosludge management, relative to landfilling. For all systems, there are net reductions in greenhouse gas emissions (–0.89, –1.43, and –1.13 tonnes CO2‐equivalent per tonne dry matter biosludge in Systems A, B, and C, respectively). System B resulted in the lowest potential eutrophication and terrestrial ecotoxicity impacts, whereas System C had the least acidification potential. The results of this analysis show that, from an environmental point of view, biochar soil amendment as an alternative method for handling pulp and paper mill biosludge is preferable to energy recovery. However, an optimal biochar system needs to factor in the social and economic contexts as well.

Place, publisher, year, edition, pages

Keywords

National Category

Environmental Engineering

Research subject

Environmental and Energy Systems

Identifiers

urn:nbn:se:kau:diva-70488 (URN)10.1111/jiec.12838 (DOI)

Note

Funding information:

This study was financially supported by the European Regional Development fund through the Swedish Agency for Economic and Regional Growth, and the NitroPortugal, H2020‐TWINN‐2015, EU coordination and support action no. 692331.

Abstract [en]

This paper evaluates the environmental impacts of different alternatives for handling of sludge from paper and pulp mills in Sweden, using Life Cycle Assessment (LCA). The common practice of incineration of biosludge with energy recovery followed by landfilling of ash (System A) was compared with the alternative of digesting sludge anaerobically to produce biogas using different digestate residue management options. The digestate produced from anaerobic digestion (AD) was assumed to be incinerated for heat energy recovery in System B or pyrolyzed for biochar production in System C to be mixed with forest soils. The impact categories considered in this work are climate change, non-renewable energy use, mineral extraction, aquatic ecotoxicity, carcinogens and non-carcinogens. The LCA results demonstrate that the two proposed systems significantly reduce the environmental impacts of biosludge management relative to incineration. An 85% reduction in the aquatic ecotoxicity impact is achieved in System C, due to the reduced mobility of heavy metals in biochar relative to ash. System C, on the whole, outperformed the other two, leading the authors to the recommendation that the use of pulp and paper mill biosludge in biogas-biochar production systems is preferable to merely recovering energy from it.

National Category

Research subject

Identifiers

Projects

FOSBE

Funder

Swedish Agency for Economic and Regional Growth, 20201239

Note

Funding text

The authors declare that there are no conflicts of interest. This study was funded by a grant from the Swedish Agency for Economic and Regional Growth , grant number 20201239 , project name Fosbe, and by a European Union grant through the Interreg Sweden-Norway program , grant number 20200023 , project name IMTRIS. Appendix A

Abstract [en]

Water is a non substitutable resource and a social good, which governments must perforce provide to its citizens in the right quantity and quality. An integrated urban metabolism model is useful in understanding the status quo of an urban water and sanitation system. By defining and measuring the values of relevant hydrological performance indicators-deliverables of the model referred to-a thorough knowledge of the present performance and the gaps, which need to be plugged en route to a sustainable urban water infrastructure, can be obtained, as demonstrated in this paper. This then forms the bedrock for decision-making and policy formulation for change to be introduced top-down as well as advice, which would enable the much needed bottom-up support to policies. The authors have chosen Delhi as the case study city, but would like to point out that this application can be reproduced for any other town/city/region of the world. The water balance within the chosen system boundaries shows that the annual unutilized flows, amounting to 1443 million cubic meters, dominate the metabolic flows of water in Delhi, and the annual groundwater withdrawal, which exceeds 420 million cubic meters, is much greater than the recharge rate, resulting in a rapid depletion of the groundwater level. There is an urgent need thereby to improve the rate of infiltration of stormwater and reduce the rate of runoff by focusing on increasing the share of permeable surfaces in the city, as well as to consider the wastewater streams as potential sources of water, while not forgetting demand side of management measures, as the pressure on the urban water system in the city is likely to intensify with a combination of population growth, economic development, and climate change in the near future. The recommendations provided by the authors towards the end of the article, can, if suitable measures are undertaken and robust policies are implemented, result in Delhi's enjoying a water surplus in the short term, and progressively attain complete sustainability with regard to the utilization of its water resources.

Abstract [en]

Aeration, as a process in pulp and paper wastewater treatment, uses the greatest share of the energy. Therefore, if the energy efficiency of the treatment has to be improved, the focus must be on aeration. A Ivey finding from the trials conducted for this paper, with effluent from a paper and pulp mill, was that the oxygen transfer coefficient could be doubled and the chemical oxygen demand could be decreased by 25%, if the effluent was pre-treated with 30 mg/I of aluminium coagulant (equivalent to 9.4 tonnes per day of AVR to 20000 cubic metres of effluent). Decrease in oxygen requirement implies decreases in aeration energy use. Pulp and paper mill effluents are not as biodegradable as municipal sewage, and the improvement in oxygen transfer properties of the effluent will have a positive influence over a longer period of time in the biological treatment. If the sludge is digested anaerobically, pre-treatment will also result in doubling the potential for methane generation. A holistic analysis of modifications to processes entails a study of the economic and environmental consequences as well. While the economic aspect is beyond the scope of this paper, only the net global warming as an environmental impact category has been studied, by taking recourse to specific emission coefficients. Of the four dosages of ferric aluminium sulphate considered in this analysis, the net greenhouse gas emissions are the least - 426 kg carbon dioxide equivalent per day when the daily consumption is 9.4 tonnes.

Abstract [en]

Pulp and paper mills use approximately 30 m3water per ton of produced paper. The process effluent has to be treated before being discharged. Mostly, the effluent is treated with aerobic biological processes using electricity for aeration, and added nutrients. The bio-sludge has low energy value and has to be disposed of. Here, we propose that effluent instead can be used as a feedstock for valuable products.

Some of the bacteria in the bio-sludge can accumulatepolyhydroxyalkanoates(PHAs). PHA is a biopolymer that has a commercial value and is an important building block for the bio-plastics industry. For an efficient PHA production, volatile fatty acids (VFAs) are needed as the feedstock substrate. Process streams rich in sugars can be fermented by the thermophilic bacteria Caldicellulosiruptor, providing acetic acid and hydrogen gas. The acetic acid can then be used as substrate for PHA accumulation.

In a case study conducted at a large integrated pulp and paper mill (>700 000 ADt/y) in Sweden, the theoretical production volume of hydrogen gas and PHA were estimated. The calculations were based on measured process effluent volumes and water quality parameters, biological process yields from laboratory and pilot scale testing, and practical experience for the unit processes. The results indicated that 0.3 kg of hydrogen gas and 1.6 kg of PHA can be produced per ADt paper or board. The additional associated benefits are significant for the mill because the demand for nutrients and energy for aeration may, at the same time, decrease by 15 to 50 percent.

By combining common biological treatment with fermentation and PHA accumulation, waste by-products can be transformed and upgraded to value-added hydrogen gas and PHA. Such a secondary side-process integration helps to shift toward the circular bioeconomy. At the same time, less energy and nutrients are needed for the wastewater treatment.

Abstract [en]

As the population of the world increases, and economies continue to develop, energy, water, materials of different types, and nutrients for food production will be needed in ever-increasing amounts. The water-energy nexus is well-understood in research circles, but one could modify this paradigm to water-nutrients/materials-energy nexus in order to incorporate recovery of substances that can be recirculated to the anthroposphere. ‘Resources’ would thus include both energy and materials (elements, compounds and mixtures – both organic and inorganic). Research in, and implementation of, recovery of different types of resources – material and energy - from wastewater (municipal, agricultural and industrial) has been going on for quite some time now. It will not be wrong to say that the imperativeness and importance of research in this field has been earnestly appreciated by academia, industry, utilities and governments alike in many parts of the world, over the last decade. This paper is a literature review of selected publications from the period 2010-2018, from a wide range of journals, focusing on resource recovery from wastewater. The selected publications originate from 44 different countries (in six continents) of the world.

Abstract [en]

As the population of the world rises and economies grow, both energy and water will be needed in ever-increasing quantities. There is a delicate balance between these two resources called the energy-water (or the water-energy) nexus. One way to reduce the energy consumption associated with wastewater treatment is to use the sludge produced during the process to generate biogas. In most countries in the developed world, the coverage, standards and reliability of wastewater treatment are high. But as the countries in the developing world are striving towards the living standards of those in the developed world, even as they combat population pressure, it is imperative that they learn from the experiences (the mistakes which occurred during the ‘learning-by-doing’ process) of the developed world. In this paper, Sweden has been used as a proxy for the developed world with a well-functioning sanitation infrastructure and reliable power supply; and India (the home country of one of the coauthors) is a proxy for the developing world which lacks the same. A very important starting point for development would be to educate people about the long-term socio-economic and environmental benefits of wastewater treatment